Loved the book, though I did get a sense of what Liane mentioned about running out of time for the current storyline. It barely has enough time to establish personalities for the characters and mention several important points for Inquisition (what are the Wardens doing, Civil War in Orlais, Mage/templar conflict) before we need to move into Valya contemplating what to do about Isseya's secret, which she learns quite a bit before the end but is hidden from the reader.
I will say that Reimas's story is, in my opinion, the most well-written part of the book, if not the best. The direct nature in which she details her father's fate ("When he learned the templars were coming, he filled his pickets with stones and walked into the lake") was very effective. Many books would have filled that story with fluff and dramatic flair, but it hits so much harder with its bluntness.
Isseya's character is a resounding success for me. During the end of the Fourth Blight and reading about Isseya's state, I couldn't help but think of Elrond and Aragorn's exchange: I give hope to men, I keep none for myself. What a wonderfully tragic transformation from the girl filled with awe and love at the beginning of the story.
I'll post more thoughts as they come, but I can appreciate how deeply you've delved into the lore to get things right here, so much so that I'm still not sure whether or not you were a massive fan before you had an inkling to pitch a DA novel.